'Dancing With The Stars' casts Snooki, Valerie Harper for season 17

Valerie Harper, whose battle with brain cancer has touched many hearts, leads one of Dancing with the Stars' most intriguing casts of recent seasons.

Harper, who reportedly is near remission, will be joined on the long-running ABC dancing competition (Sept. 16, 8 p.m. ET/PT) by a mix of personalities and newsmakers announced this morning on Good Morning America. They include Jersey Shore star and recent mom Nicole "Snooki" Polizzi; Glee's Amber Riley; Leah Remini of The King of Queens and The Talk, who made news recently with reports of her departure from the Church of Scientology; and Jack Osbourne, brother of former Dancing competitor Kelly Osbourne, who last year learned he had multiple sclerosis.

Other Season 17 stars pairing up with professional partners include singer Christina Milian, formerly of time-slot competitor The Voice; actress Elizabeth Berkley Lauren, a trained dancer known for different kinds of dance moves in Showgirls; Bill Nye, the beloved science guy; comedian Bill Engvall; former NFL star Keyshawn Johnson; High School Musical star Corbin Bleu; and Brant Daugherty of Army Wives and Pretty Little Liars.

"I feel like it's one of the best (fields) we've had in years. Every single person justifies their place," executive producer Conrad Green says of the new dancing dozen. "We wanted to get people with compelling stories. We wanted to get people who will be able to put on a show for us. We wanted something that would appeal to every age of the family and we've got that with this cast."

A strong field could help the long-running dance competition as it shrinks from two shows a week to one, eliminating the Tuesday results show.

"It's a critical season for us. We're going to one night a week. We really want to make a bang with it and we know the single biggest determining factor in how well the show does is the cast," Green says.

The new dancers are excited about the opportunity.

"I've always been a fan of the show and I am in the best shape of my life, so I feel if I can lose 50 pounds in six months, I can learn the waltz," says Polizzi, who gave birth to son Lorenzo last year, in an e-mail.

Standing out among the stars is Harper, best known for playing Rhoda Morgenstern on The Mary Tyler Moore Show, who in March said her life expectancy was three months. However, she is close to remission, a doctor says in an upcoming NBC special.

"She's feeling great at the moment. Her treatment is working out wonderfully. I think she's very much seizing life and doing things she wants to do and trying to give a positive message to people who are suffering from some of these terrible illnesses, that you can still get out and do things and really make the most of the time you have," Green says of the 74-year-old actress, who was a dancer in her 20s. "It's an incredibly positive and quite moving story."

Osbourne, a TV producer and son of Ozzy and Sharon Osbourne, says his family - including his sister, Kelly, who finished third in 2009 - encouraged him to participate.

"A large part of it was talking with my family, (including) my sister, who had done it (and) had such a good time and my wife really loving the show," he says. "And having been diagnosed with MS and going through that whole roller coaster, I saw it as an opportunity, almost a greater responsibility to keep MS awareness on people's minds. Although there is treatment for it, we're no closer to a cure. I'm trying to raise awareness that way."

He has been practicing with partner Cheryl Burke and health hasn't been an issue.

"Touch wood right now, I'm fine, but herein lies the different thing with MS. I'm fine one minute and you wake up the next day and your legs might not work," he says.

He expects family members to be in the audience to support him when they're in town: "Kelly will be there. She's probably going to be secretly hoping I don't do better than she did."

Dancing could use a buzzworthy field, as the once red-hot series has seen its ratings drop (and viewership age) in recent years. Last spring's season averaged 15.4 million viewers, down 15% from the previous spring though up slightly from last fall.

That's one reason the show is being squeezed from three hours over two nights into a single two-hour episode on Mondays, which will include performances and eliminations. As the season progresses and the field narrows, there will be more room for outside singing and dancing performances.

"This gives us a chance to shake up the whole show. Rather than having what we had before, which is a performance show on a Monday and a variety show on Tuesday, we're very determined to pull the best of both of those things into one really compelling Monday night show," Green says. "We want the show to feel live, we want it to feel loose, we want it to be a little bit more unpredictable."

To accommodate the new schedule, the show will weigh judges' and viewer votes differently. Each elimination will be determined by the judges' vote from that evening combined with the viewer vote from the previous week. (There will be no elimination in Week 1).

"In an odd way, it gives the couples a bit of an extra chance" if they perform poorly in a given week, Green says.

The show also is eliminating the skybox area where host Brooke Burke-Charvet interviewed dancers after their performances, moving that area to the floor near the judges. Burke-Charvet and host Tom Bergeron will interview the couples from the floor before and after their performances.

The Season 17 stars are learning new steps in preparation for the premiere.

Osbourne, who became a father last year and is expecting a second child with his wife, Lisa, says he doesn't have dance experience but that practice with Burke is going well and that he hopes to make it to the finals.

"If I'm rating myself, I'm awesome, but I don't know how universally I rate. I think I'm OK. Cheryl seems to think we have something to work with," he says. "Cheryl is awesome. I couldn't have landed a better dance partner. We have a similar sense of humor. She keeps the mood light, which is always a good thing."

And don't expect the kind of dancing Polizzi displayed on Jersey Shore, as her style has changed with maternity.

"I was a mess when I danced in clubs. Now that I'm a mom, I dance like a mom and I love it," she says.

Although ratings have been down and Dancing faces tough competition from the younger-skewing Voice on Monday, most reality shows are seeing viewer loss and Green says the show still has much promise.

Downturns "are true for pretty much everybody at the moment. We were still, most weeks, the most-watched reality show of all," he says. "In many ways, we've got a lot of strengths that other shows don't have. I think it's worth holding on to that before people start writing obituaries."